This is a Shannon award providing partial support for the research projects that fall short of the assigned Institute's funding range but are in the margin of excellence. The Shannon award is intended to provide support to test the feasibility of the approach; develop further tests and refine research techniques; perform secondary analysis of available data sets; or conduct discrete projects that can demonstrate the PI's research capabilities or lend additional weight to an already meritorious application. The abstract below is taken from the original document submitted by the principal investigator. DESCRIPTION: (Adapted from the Investigator's abstract): This once revised application seeks to determine the characteristics of the humoral and cellular immune response following oral immunization with avirulent Salmonella typhimurium (S. typhimurium) strains expressing Porphyromonas gingivalis (Pg) antigens. It focuses on the possible virulence factor hagB hemagglutinin. There are three Specific Aims. In Specific Aim 1, the optimum immunization regimens, that is the size, number and frequency of doses of the immunogen for priming and boosting will be determined. The kinetics and isotype distribution of antibodies in serum, saliva, bile, gut washes and feces will be measured. Responses will also be examined at the cellular level in spleen, gut lamina propria, and salivary glands using the ELISPOT assay. TH1 and Th2 cells in Peyer's patches and spleen will be determined by measuring cytokine profiles. Specific Aim 2 will examine the effect of copy number of the plasmid, pre-existing antibody to the carrier strain, fusion of antigens with mucosal adjuvants and presence of the Salmonella virulence plasmid in the carrier strain. Specific Aim 3 will determine the effects of immunization with cloned antigens in experimental in vitro and in vivo models. It is expected that these approaches will improve understanding of the mechanisms by which Pg causes disease, and will be useful in designing a potential vaccine.